In order to prevent explosion of a combustible gas after reaching a certain concentration to ensure production safety, a combustible gas detecting and alerting device is usually arranged in a factory or facility wherein a combustible gas is produced and used. A major constituent of such combustible gas detecting and alerting device is a combustible gas detector. Current combustible gas detectors mainly consist of a gas sensitive element, a gas sensitive element fixing sleeve, a rain cover and a cable entry means.
Currently, a combustible gas detector of such a structure is not secure in design, thus, when applied in a combustible gas environment, there is a risk of creating a detonation in the surrounding environment, and providing a more explosion proof design often cannot be satisfied. Thus, an explosion-proof encapsulation is required. A traditional method to form an explosion-proof encapsulation for a combustible gas detector is to encapsulate a catalytic bead in a stainless steel casing, which has a flame catching and extinguishing sintered sheet, and the end of the casing is poured with epoxy to be leak-proof. In accordance with the standard for explosion-proof authentication in Europe and North America, it is required that for any explosion-proof casing, if sealed using a sealant, a bonding length between the sealant and the casing in the sealing direction shall be no less than 3 mm. Besides, the design of sealing with a sealant requires a sufficient size so that the explosion proof effect can be ensured. Thus, the size of a traditional design is usually large, and a small and portable combustible gas detector cannot be realized.
Usually, measurement means of a combustible gas detector include: a thermal conductivity detector, an infrared detector, and catalytic combustion detection, etc. These detection means mostly adopt the manner of heat measurement, that is, detecting a combustible gas by influence on the temperature or heat of a sensitive element caused by flow, infrared absorption or combustion of a combustible gas. However, according to common knowledge, any detection involving heat measurement will necessarily be influenced by a change in temperature of the ambient environment. Thus, a heat-measuring sensor usually requires a reference detector or a reference element for canceling influence on the measurement of the detecting element caused by environmental factors such as temperature, humidity, pressure, airflow, etc. Obviously, the reference element needs to be infinitely consistent with the detecting element in term of several factors such as temperature, humidity, pressure and airflow, etc. such that a maximal compensation effect can be achieved. Unfortunately, the compensation effect of reference elements in current combustible gas detectors, especially catalytic combustion or thermal conductivity sensors, are far from ideal due to the product design and the less advanced production process. That is to say, currently, combustible gas detectors manufactured by most of the manufacturers still have significant effects of temperature, humidity, pressure and airflow etc. although undergoing compensation by a reference element.